Musculocutaneousnerven

The musculocutaneous nerve, known in Swedish as Musculocutaneousnerven, is a branch of the brachial plexus. It carries nerve fibers from the C5 to C7 nerve roots and provides motor innervation to the anterior compartment of the arm, as well as sensory innervation to the lateral forearm via its terminal branch, the lateral antebrachial cutaneous nerve.

Course and branches: The nerve typically pierces the coracobrachialis muscle, then descends between the biceps brachii and brachialis. It travels with the brachial artery and emerges laterally to the biceps tendon at the elbow, continuing as the lateral antebrachial cutaneous nerve. Its motor branches supply coracobrachialis, biceps brachii, and brachialis.

Function: Functionally, the musculocutaneous nerve enables elbow flexion and forearm supination, with particularly strong assistance from the biceps brachii. Sensory-wise, it provides sensation to the lateral aspect of the forearm.

Clinical significance: Injury or compression can result from upper-arm trauma, humeral fractures, axillary region compression, or during shoulder and upper-arm surgeries. Clinical signs include weakness of elbow flexion and forearm supination, and sensory loss over the lateral forearm. Evaluation typically involves clinical examination and nerve conduction studies; management depends on the cause and extent of injury, ranging from conservative treatment to surgical repair or nerve grafting in severe cases.

Variations: Anatomical variations exist; in some individuals the lateral antebrachial cutaneous nerve may arise from the median nerve or from different branches, and the precise course can vary slightly.